public Vector3 shading(Vector3 pos, Vector3 norm, Ray ray, Actor actor, bool isShade)
{
// 点光源
var l = light - pos;
var l2 = l.LengthSquared();
l.Normalize();
// 視線
var dir = ray.Position - pos;
dir.Normalize();
// ハーフベクトル
var h = dir + l;
h.Normalize();
var ln = Vector3.Dot(l, norm);
var hn = Vector3.Dot(h, norm);
if (ln < 0) ln = 0;
if (hn < 0) hn = 0;
var dst = actor.GetColor(isShade ? 0.0f : ln, hn, pos);
// 光源の色の反映
dst.X *= lightColor.X;
dst.Y *= lightColor.Y;
dst.Z *= lightColor.Z;
// 光の強さの適当な補正
//dst *= Math.Min(1.5f, 500000.0f / (10000.0f + l2));
//dst *= Math.Min(1.0f, l.Y + 0.1f);
return dst;
}
Vector3 trace(Ray ray, Actor sender, int depth)
{
if (depth > MAX_DEPTH) return Vector3.Zero;
var nearestNorm = Vector3.Zero;
var nearestPos = Vector3.Zero;
Actor nearestActor = null;
var color = Vector3.Zero;
foreach (var actor in actors)
{
if (actor == sender) continue;
var norm = Vector3.Zero;
var pos = Vector3.Zero;
if (actor.isIntersect(ray, out norm, out pos))
{
var d1 = pos - ray.Position;
var d2 = nearestPos - ray.Position;
if (nearestActor == null)
{
nearestActor = actor;
nearestNorm = norm;
nearestPos = pos;
}
else if (d1.LengthSquared() < d2.LengthSquared())
{
nearestActor = actor;
nearestNorm = norm;
nearestPos = pos;
}
}
}
if (nearestActor == null)
{
return Vector3.Zero;
}
var crl = nearestActor.material.reflection;
var crr = nearestActor.material.refraction;
var cr = nearestActor.material.refraction;
// 反射ベクトル
var v = ray.Direction - 2 * Vector3.Dot(nearestNorm, ray.Direction) * nearestNorm;
v.Normalize();
var reflectionRay = new Ray(nearestPos, v);
// 屈折ベクトル
var vn = Vector3.Dot(ray.Direction, nearestNorm);
float eta = 1.5f; // 屈折率
Vector3 t;
if (vn < 0)
{
var d = 1 - (1 + vn) * (1 + vn) / (eta * eta);
if (d < 0)
{
t = Vector3.Zero;
}
else
{
t = (-vn / eta - (float)Math.Sqrt(d)) * nearestNorm + (1 / eta) * ray.Direction;
}
}
else
{
var d = (1 - vn) * (1 - vn) / (eta * eta);
if (d < 0)
{
t = Vector3.Zero;
}
else
{
t = -(vn / eta - (float)Math.Sqrt(d)) * nearestNorm + eta * ray.Direction;
}
}
t.Normalize();
var refractionRay = new Ray(nearestPos, t);
var reflect = nearestActor.material.reflection <= 0.00001f ? Vector3.Zero : trace(reflectionRay, nearestActor, depth + 1);
var refraction = nearestActor.material.refraction <= 0.00001f ? Vector3.Zero : trace(refractionRay, nearestActor, depth + 1);
bool shade = false;
foreach (var actor in actors)
{
if (actor == nearestActor) continue;
var norm = Vector3.Zero;
var pos = Vector3.Zero;
var d = shader.light - nearestPos;
d.Normalize();
if (actor.isIntersect(new Ray(nearestPos, d), out norm, out pos))
{
shade = true;
break;
}
}
var diffuse = shader.shading(nearestPos, nearestNorm, ray, nearestActor, shade);
return
nearestActor.material.diffuse * diffuse +
nearestActor.material.reflection * reflect +
nearestActor.material.refraction * refraction;
}